1. Field of the Invention
The invention relates to a deep-dyeable polyester fiber, more particularly to a polyester fiber having very high dyeability as well as soft hand and high pilling resistance.
2. Description of the Prior Art
Polyester fibers have excellent physical properties and, thus, are broadly utilized for clothing and industrial materials. However, polyester fibers have a drawback in that they are hard to dye in boiling water under normal pressure. In order to improve the dyeability of a polyester fiber, there has been proposed the use of polyesters containing various third components. Further, it is described, in British Pat. No. 735,171, that the affinity for a dyestuff of a polyester fiber can be improved by subjecting the polyester fiber to heat treatment at a temperature higher than 200.degree. C. after drawing. However, in conventional polyester fibers, further improvement in the dyeability is still earnestly desired.
Further, a polyester fiber has a relatively hard hand. Therefore, the polyester fiber has been mainly recommended as a material for clothing for gentlemen. However, a woven or knitted fabric having a close texture and a soft hand which is useful as clothing for ladies, particularly autumn and winter clothing can not be obtained from the conventional polyester fiber.